The California DMV form is called a Statement of Facts, and it is to be signed by a state certified lighting inspection station (many repair shops have this).
One advantage of getting a kit from a place like Baja Designs is they will include the forms.
If you get a blank statement of fact in CA, you should add the following:
"The vehicle desribed above has an operating headlight with high and low beams, high beam indicator, taillight, stoplight, license plate light, turn signals, rear reflex reflector, front and rear brakes and horn.
The vehicle complies with the requirements for a street motorcycle as described in California Highway Patrol publication 888"